Our experience to date suggests that lecithin administration by itself is not a satisfactory treatment for Alzheimer's disease, and that this disorder might not be a unitary one. Thus, during the next two years, we shall broaden our attempt to palliate the behavior symptoms of Alzheimer's disease and of normal aging, and in conjunction shall expand our study of the neurological, neurochemical, and neuropsychological correlates of these conditions. The goals of the proposed research will be to: 1. Search for biochemical, physiological, and behavioral variables that might be used to subdivide patients previously diagnosed as having Alzheimer's disease. We shall measure spinal fluid levels of several peptides, neurotransmitter metabolites, and proteins (biochemistry), urine levels of melatonin (physiology), and performance on a judiciously selected battery of cognitive tests (behavior). 2. Refine our current battery of tests in order to obtain a better understanding of the specific behavioral losses in aging and dementia and thereby identify the areas where we might find changes with treatment. A related goal is to introduce tests that have ecological validity, that is, tests that measure behaviors that are comparable to the patients' daily activities. 3. Perform clinical trials, in patients with Alzheimer's disease and in healthy elderly subjects, using drugs that enhance cholinergic neurotransmission. We shall compare the effects on behavior of lecithin in combination with oral physostigmine, and lecithin in combination with piracetam. 4. Perform clinical trials, in patients with Alzheimer's disease and in healthy elderly subjects, using drugs that enhance monoamine neurotransmission. We shall measure the effects on behavior of tyrosine and tryptophan, precursors of dopamine and serotonin respectively, in those patients with Alzheimer's disease who show a specific deficit in monomine metabolites in CSF. 5. Devise tests that teach patients strategies of learning, and then measure their effectiveness in subsequent memory performance. This procedure will enable us to identify patients who might be suitable for long-term mnemonic training that would be beneficial in their daily acitivities at home.